Many commercial and military technologies require the use of multiple transmission line types, such as coaxial cables, stripline, microstrip, waveguides, and optical fibers. These transmission lines offer different advantages and disadvantages, so it is desirable to transition between two different transmission line technologies within a module or system. Many of these transmission lines transitions tend to only operate efficiently over a narrow frequency band, which greatly reduces the amount of signal spectrum that can flow through them.
In particular, coaxial and waveguide transmission lines are used in a number of electrical modules and systems. A classic example is a waveguide fed antenna (such as a horn) with the waveguide having a signal input from a coaxial cable. This transition consists of the inner conductor of the coaxial line being probed into the waveguide and launching its signal into the waveguide. This transition and other coaxial to waveguide transmission line transitions are used in many applications. Commercially sold or academically documented coaxial-to-waveguide transitions are efficient (low-loss), but very frequency band limited. A need exists for a coaxial to waveguide transmission line transition that operates over a wider frequency band than currently-available transitions and maintains a high level of efficiency.